Improvement in leaching tan-bakk



ABRAHAM STEERS, OF NEW YORK, N. Y., ASSIGNOR TO HIMSELF, HENRY L. ELDER, AND

S H. KENNEDY, OF PHILADELPHIA, PENNSYLVANIA.

Letters Patent -No. 68,010, dated.' August 20, 1867.

IMPROVEMENT IN LEAGHING TAN-BARE.

'alle dphuls tuant tu in tipa tta atut matutina am nf the same.

TO ALL WHOM IT MAY CONCERN:

Be it known that I, ABRAHAM STEERS, of the city, county, and State of New York, have invented a new and useful Improvement for the Leaching oflTan-Bark.; and I do hereby declare that the following'is a full, clear, and exact description thereof, which will enable others skilled in the art to make anduse the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure 1 represents a longitudinal vertical section of this invention, taken in the plane indicated bythe line :r 2:, iig. 2. v

Figure 2 is a plan or top view ofthe same.

Similar letters of reference indicate like parts.

This invention relates to a new process for leaching tan-bark, in which the ground bark is first washed out cold with water or weak tanning-liquor, then heated with steam, and finally washed out with water let on from below. The tan-bark to beextracted is enclosed in a leach, by preference round and detached, and provided with a perforated false bottom and a perforated false top, between which the tan-bark is enclosed. The menl struum is admitted from below through the false bottom, and passed from one leach to the other, and after all the strength has been extracted which can be got out by a cold menstruum, the bark is steamed from below, and

the menstruum is again let on in an upward current, so that the formation of channels in therbark is prerented,.

and the menstruum is not permitted to ru'n through the bark without washing out its strength.

A A represent a series of'leaches, made of wood or any other suitable material, and round, in preference to any other form, becausefin a round leach the menstruum and the steam are enabled to act on the bark'more uniformly than in a leach with a square or angular cross-section. Each leach is provided with a perforated false top, A, and a perforated falsobottom, c, and the space between this false bottom and top is llcd with tan-bark or other material to be extracted. The menstruum used in washing out the bark is injected by a pump, B, hnd pipe, C, which connects with the iirst leach by means of a branch pipe, C, and with the second leach by a branch pipe, C', and so on. The branch pipes C C lead to upright tubes CZ d', which rise from a horizontal trough or channel, and which communicate with the leaches by stop-valves ffleading to the spaces below the false bottoms b. A stop-valve, g, also forms a connection between the 4leach A and the second upright tube d', and; this stop-valve extends from an annular space, ajust belowthe top a, and communicating with the space above said false top through a series of channels, z'. A similar stopvalve connects the second leach with the thirdy upright tube, and so forth. Stop-valves j, which are opened and closed from the tops of the leaches, are inserted in the bottoms of said leaches, and form a direct communication between the spaces below the false bottoms' and the horizontal trough or channel e, and the spaces` below said perforated false bottoms are occupied by steam-coils c, which are supplied with steam through apipe, Z, `and branch pipesm. From said steam pipe extend also the branch pipes n o, the former' into thespace above the perforated falseY tops, and the latter into upright tubes pp', leading down through the leaches in the spaces below theperforated false bottoms. Instead of injecting live steam through the pipes Z m n.0, exhaust steam may be injected into the leaches through pipes mi?. The leachcs are charged through man-holes (j in their tops, and through tubes r extending frommsaid manholes down in the spaces below the perforated' false tops, and they lare discharged through holes s in their sides, and through other holes t and tubes u `in their bottoms. Allthese holes or tubes are closed by suitablev m'an-hole plates', which can be readily and 'easily removed.

The operation is as follows: The spaces between the perforated false bottoms and tops in the leaches are filled with ground bark, andi-cold water or'weak tan-liquor is pumped through the pipe C and tube OZ` into the bottom part of the first leach, causing the liquid to rise through the perforatedV false bottom, and through the ground bark 'to the space'labove the perforated false top, whence it passes through the stop-valve y, which must be open, and through the tube d and valvef, which is also open, into the bottom part of the second leach, where it rises again through the bark, and so on through the entire series of leaches.' From the last leach the men struum `is caused to How back through the channel e to the tank '.I, whence it is again injected into the rstxstill and caused to pass through all the stills, until it has reached the requisite strength. The menstruumg-b g passed in an upwrd direction through. the bark, is diffused more evenly through the entire mass, and

formation of channels in the bark is prevented, whereas in downward leaching the menstruum is liable to form channels in the bark through which it passes, and a large percentage of the bark is not brought in contact with the menstruum. Furthermore, by treating the bark first with cold water, much of the strength is extracted which cannot bereached if the bark is heated at the beginning of the operation. After the bark has been sui`- iciently extracted by the action ofthe menstruurn, I stop the operation of the purnp B, and let on steam, using live or exhaust steam, either direct or through the medium ot' the coil c, and after having heated the lbark' by fthe action of the steam, I start the pump again, and by these means the full strength ofthe bark is extracted.

In order to drive the liquor from leach to leach, I let on steam fronn above, and by the perforated false tops cr perforated sectional guard or channel L, the bark is prevented from passing into th'e.pipes with the liquor. For

the purposes 'of tanning, there should be a suicient number of leaches to have the liquor thrown into them from the back leaches cold. The forward leach or leaches, which contain thc fresh bark, and from which is drawn the liquor for use, are used asiilterers to obtain better conditioned liquor for tanners purposes, and said leach or leaches are also desirable for the purpose of more perfectly damping and preparing the bark toreceive heat without loss or injury to the quality or quantity o`i` the extractable tanning or astringent salts inherent in the bark. By the action of the pump, an impelled current of liquor or water is forced through the lea-ches, and the force of the pump can be assisted by the action ot` the steam. By'this forced current all obstructions which nay form in the pipes are forced out, and the apparatus is always kept in proper working order.

What I claim as new, and desire to secure by Letters Patent, is-

1. Passing the menstruum through the bark contained in the leach or leaches in an upward instead of in a downward direction, substantially as and forthe purpose described.

2. Heatingthe bark With live or exhaust steam, after the same has been partially extractedby the cold menstruum, and then Washing it out with water or weak tan-liquor, substantially as and for the purpose set forth.

3. They use of the perforated false top or perforated guard-channel h in combination with the still, to prevent th`e bark from passing into the pipes with the liquor, substantially as described. Y

4. `The use oi a forced current of liquid or duid through the mattei-,operated on, and the adjustment ofthe second connecting pipes and valves for that purpose, whereby the force of the. pun/1p can be used to clear out obstructions in the piping, as set forth. v l

5. Forcing the liquor through aiseries of leaehes by the action of a. pump, or by means of steam, or both combined. I

ABRM. STEER'S.

Witnesses:

WM. F. McNAMAuA, ALEX. F. ROBERTS.v 

